Pro-social Behavior in the Global Commons: A North-South Experiment

Differences in group affiliation may affect the level of cooperation in global commons situations such as programs for the conservation of resources which generate benefits that transcend state boundaries. We design a real-time, cross-cultural common pool resource (CPR) experiment purposely using participants from cultures that derive different benefits from biodiversity (extraction versus conservation) to analyze the effect of group affiliation on cooperative behavior. In addition, we elicit real donations to local and international conservation funds to augment our CPR results. In the CPR environment, we find evidence that group affiliation affects hehavior such that heterogeneity contributes to over-extraction in the commons. In the donation stage, we show that nationality affects the distribution of donated earnings between the local and global funds. We also examine the possibility that altruistic preferences to donate to a conservation fund are endogenous, in that they reflect the level of cooperation in the CPR game.common pool resource, group affiliation, cooperation, cross-culture, dicator game, endogenous preferences, experiment

Behavioural Development Economics: Lessons from field labs in the developing world

Explanations of poverty, growth and development more generally depend on the assumptions made about individual preferences and the willingness to engage in strategic behaviour. Economic experiments, especially those conducted in the field, have begun to paint a picture of economic agents in developing communities that is at some variance from the traditional portrait. We review this growing literature with an eye towards preference-related experiments conducted in the field. We rely on these studies, in addition to our own experiences in the field, to offer lessons on what development economists might learn from experiments. We conclude by sharing our thoughts on how to conduct experiments in the field, and then offer a few ideas for future research.

Risk Attitudes and Well-being in Latin America

A common premise in both the theoretical and policy literature on development is that people remain poor because they are too impatient to save and too risk averse to take the sort of chances needed to accumulate wealth. The empirical literature, however, suggests that this assumption is far from proven. We report on field experiments designed to address many of the problems confounding previous analyses of the links between risk preferences and well-being. Our sample includes more than 3,000 participants who were drawn representatively from six Latin American cities: Bogotá, Buenos Aries, Caracas, Lima, Montevideo, San José. In addition to the experiment which reveals interestingcross-country differences, participants completed an extensive survey that provides data on a variety of well-being indicators and a number of important controls. Focusing on risk preferences, we find little evidence of robust links between risk aversion and wellbeing. However, when we analyze the results of three treatments that add elements of reality to the decision problem, we see that these, more subtle, instruments correlate better with well-being, even after controlling for a variety of other important factors like the accumulation of human capital and access to credit.risk aversion, ambiguity aversion, loss aversion, risk pooling, well-being, Latin America

Risk Attitudes and Well-Being in Latin America

A common premise in both the theoretical and policy literatures on development is that people remain poor because they are too impatient to save and too risk averse to take the sort of chances needed to accumulate wealth. The empirical literature, however, suggests that this assumption is far from proven. We report on field experiments designed to address many of the issues confounding previous analyses of the links between risk preferences and well-being. Our sample includes more than 3,000 participants who were drawn representatively from six Latin American cities: Bogotá, Buenos Aires, Caracas, Lima, Montevideo, San José. In addition to the experiment which reveals interesting cross-country differences, participants completed an extensive survey that provides data on a variety of well-being indicators and a number of important controls. Focusing on risk preferences, we find little evidence of robust links between risk aversion and well-being. However, when we analyze the results of three treatments designed to better reflect common choices made under uncertainty, we see that these, more subtle, instruments correlate better with well-being, even after controlling for a variety of other important factors like the accumulation of human capital and access to credit.risk aversion, ambiguity aversion, loss aversion, risk pooling, well-being, Latin America

Experiments and Economic Development: Lessons from Field Labs in the Developing World

Along with the traditional primitives of economic development (material preferences, technology, and endowments), there is a growing interest in exploring how psychological and sociological factores (e.g., bounded rationality, norms, or social preferences) also influence economic decisions, the evolution of institutions, and outcomes. Simultaneously, a vast literature has arisen arguing that economic experiments are important tools in identifying and quantifying the role of institutions, socialnorms and preferences on behavior and outcomes. Reflecting on our experience conducting experiments in the field over more than five years, we survey the growing literature at the intersection of these two research areas. Our review has four components. In the introduction we set the stage identifying a set of behavioral factors that seem to be central for understanding growth and economic development./ We then divide the existing literature in two piles: standard experiments conducted in the field and on how to econometrically identify sociological factors in experimental data. We conclude by suggesting topics for future research.experimental economics, behavioral economics, institutions, social preferences, poverty, development

Field host range of Apanteles opuntiarum (Hymenoptera: Braconidae) in Argentina, a potential biocontrol agent of Cactoblastis cactorum (Lepidoptera: Pyralidae) in North America

Field exploration in Argentina for cactophagous lepidopteran hosts parasitized by the recently described braconid parasitoid Apanteles opuntiarum Martínez & Berta (Hymenoptera: Braconidae) revealed a host range restricted to Cactoblastis cactorum (Berg) (Lepidoptera: Pyralidae) and C. doddi. Field collections of cactophagous larvae parasitized by the congeneric and sympatric parasitoid A. alexanderi included the host species C. bucyrus, Sigelgaita nr. chilensis, Tucumania sp., Tucumania tapiacola and Salambona sp. If a narrow host range for A.opuntiarum is confirmed in quarantine with North American cactus-feeding species, then this parasitoid could be released as a biological control agent for C. cactorum with little or no risk to non-target species.Las exploraciones de campo en Argentina de larvas hospedadoras cactófagas parasitadas por Apanteles opuntiarum Martínez & Berta (Hymenoptera: Braconidae), un bracónido recientemente descripto, revelaron un espectro de hospedadores restringido a Cactoblastis cac­torum (Berg) (Lepidoptera: Pyralidae) y C. doddi. Las colecciones de campo de larvas cactófagas parasitadas por la especie congenérica y simpátrica A. alexanderi identificaron a C. bucyrus, Sigelgaita nr. chi­lensis, Tucumania sp., Tucumania tapiacola y Salambona sp. como es­pecies hospedadoras. Si se confirma en cuarentena el estrecho rango de hospedadores de A. opuntiarum sobre especies norteamericanas que se alimentan de cactus, podría ser liberado como agente de con­trol biológico de C. cactorum, con bajo riesgo o ninguno a especies no blanco.Fil: Varone, Laura. Fundación para el Estudio de Especies Invasivas; ArgentinaFil: Logarzo, Guillermo Alejandro. Fundación para el Estudio de Especies Invasivas; ArgentinaFil: Martinez, Juan Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales ; ArgentinaFil: Navarro, Fernando. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto Superior de Entomología; ArgentinaFil: Carpenter, James E.. United States Department of Agriculture; Estados UnidosFil: Hight, Stephen D.. United States Department of Agriculture; Estados Unido

Carboxyl-modified single-wall carbon nanotubes improve bone tissue formation in vitro and repair in an in vivo rat model.

The clinical management of bone defects caused by trauma or nonunion fractures remains a challenge in orthopedic practice due to the poor integration and biocompatibility properties of the scaffold or implant material. In the current work, the osteogenic properties of carboxyl-modified single-walled carbon nanotubes (COOH-SWCNTs) were investigated in vivo and in vitro. When human preosteoblasts and murine embryonic stem cells were cultured on coverslips sprayed with COOH-SWCNTs, accelerated osteogenic differentiation was manifested by increased expression of classical bone marker genes and an increase in the secretion of osteocalcin, in addition to prior mineralization of the extracellular matrix. These results predicated COOH-SWCNTs' use to further promote osteogenic differentiation in vivo. In contrast, both cell lines had difficulties adhering to multi-walled carbon nanotube-based scaffolds, as shown by scanning electron microscopy. While a suspension of SWCNTs caused cytotoxicity in both cell lines at levels >20 μg/mL, these levels were never achieved by release from sprayed SWCNTs, warranting the approach taken. In vivo, human allografts formed by the combination of demineralized bone matrix or cartilage particles with SWCNTs were implanted into nude rats, and ectopic bone formation was analyzed. Histological analysis of both types of implants showed high permeability and pore connectivity of the carbon nanotube-soaked implants. Numerous vascularization channels appeared in the formed tissue, additional progenitor cells were recruited, and areas of de novo ossification were found 4 weeks post-implantation. Induction of the expression of bone-related genes and the presence of secreted osteopontin protein were also confirmed by quantitative polymerase chain reaction analysis and immunofluorescence, respectively. In summary, these results are in line with prior contributions that highlight the suitability of SWCNTs as scaffolds with high bone-inducing capabilities both in vitro and in vivo, confirming them as alternatives to current bone-repair therapies

Statistical Properties of Avalanches in Networks

We characterize the distributions of size and duration of avalanches propagating in complex networks. By an avalanche we mean the sequence of events initiated by the externally stimulated `excitation' of a network node, which may, with some probability, then stimulate subsequent firings of the nodes to which it is connected, resulting in a cascade of firings. This type of process is relevant to a wide variety of situations, including neuroscience, cascading failures on electrical power grids, and epidemology. We find that the statistics of avalanches can be characterized in terms of the largest eigenvalue and corresponding eigenvector of an appropriate adjacency matrix which encodes the structure of the network. By using mean-field analyses, previous studies of avalanches in networks have not considered the effect of network structure on the distribution of size and duration of avalanches. Our results apply to individual networks (rather than network ensembles) and provide expressions for the distributions of size and duration of avalanches starting at particular nodes in the network. These findings might find application in the analysis of branching processes in networks, such as cascading power grid failures and critical brain dynamics. In particular, our results show that some experimental signatures of critical brain dynamics (i.e., power-law distributions of size and duration of neuronal avalanches), are robust to complex underlying network topologies.Comment: 11 pages, 7 figure

First record of Vespula vulgaris (Hymenoptera: Vespidae) in Argentina

Vespula vulgaris (Linnaeus) es un véspido social nativo de la región Holártica. En este trabajo reportamos la primera detección de esta especie en Argentina. Obreras de esta avispa fueron capturadas cerca de la ciudad de San Carlos de Bariloche (Argentina) en Febrero de 2010, mientras se tomaban muestras de otra avispa invasora, Vespula germanica (Fabricius) o chaqueta amarilla, de morfología externa y hábitos similares a la anteriormente mencionada. Además, detallamos algunos caracteres de identificación y características biológicas.Vespula vulgaris (Linnaeus) is a social vespid native to the Holarctic region. The first detection of this species in Argentina is here reported. Workers were captured close to San Carlos de Bariloche (Argentina) during February 2010, while sampling for another successful invader, the German wasp or Yellowjacket, Vespula germanica (Fabricius). Both these wasp species are very similar morphologically and share a number of common habits. Also, some identification features and biological characters are here explained .Fil: Masciocchi, Maité. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnologia Agropecuaria. Centro Reg.patagonia Norte. Estacion Exptal.agrop.s.c.de Bariloche. Laboratorio de Ecologia de Insectos; ArgentinaFil: Beggs, Jacqueline R.. The University Of Auckland; Nueva ZelandaFil: Carpenter, James M.. American Museum Of Natural History; Estados UnidosFil: Corley, Juan Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnologia Agropecuaria. Centro Reg.patagonia Norte. Estacion Exptal.agrop.s.c.de Bariloche. Laboratorio de Ecologia de Insectos; Argentin